Modeling underwater sound propagation in an arctic shelf region with an inhomogeneous bottom.

The seabed data from the Kara Sea (a part of the Arctic Shelf) are used to build a low-frequency (up to 250 Hz) acoustic waveguide model and study sound propagation in this region. A 30-m deep, well-mixed, and homogenous water layer over a flat seafloor is considered. The seabed's acoustic model is based on the spatial distribution of a sound speed recorded during a three-dimensional seismic survey in the Kara Sea, as well as density data from core sample analysis.

Using discrete low-frequency components of shipping noise for gassy sediment characterization in shallow water.

This work shows that normal-mode attenuation coefficients can be extracted from ship noise and used to estimate the sound speed in gas-saturated sediments. In an experiment in the Sea of Galilee, a research vessel served as a noise source approaching a vertical hydrophone array at a constant speed. Twelve narrow-band components of the vessel noise in the frequency band 20-100 Hz were identified and mode filtered to estimate the normal-mode attenuation coefficients.

Modeling the effects of linear shallow-water internal waves on horizontal array coherence.

The coherence length of a horizontal array is the maximum separation between two points where coherent processing gives useful gain when a distant source is at broadside. In shallow water, the coherence length is limited by the environmental variability caused by several relevant oceanographic processes. In the present study, a statistical model is developed that quantifies how one oceanographic process, linear internal waves, affects the coherence length.